A way station between the splanchnic and systemic circulation which maintains the body’s metabolic processes by processing dietary amino acids, carbohydrates, lipids, vitamins, and removes toxins and microbes in the splanchnic circulation, synthesizes many of the plasma proteins and detoxifies and excretes into bile waste products.

Liver disease causes 2 million deaths per year worldwide.

The liver has numerous synthetic, storage, and excretory functions.

The liver synthesizes many of the coagulation factors necessary for hemostasis.

Adequate liver function is required for intestinal absorption of vitamin K, a fat-soluble vitamin critical to the formation of numerous clotting factors.

The liver also is responsible for the metabolism of circulating estrogens and the secretion of bilirubin, a product of normal heme catabolism.

The hepatic portal vasculature is also an important component of the circulatory system, which enables the immediate processing of nutrients absorbed in the small intestines.

Possesses ability to regenerate within a short period of time.

Conventionally divided into right, left, caudate and quadrate lobes, which does correlate with the functional segments of the liver.

The quadrate and greater part of the caudate lobe on the posterior aspect of the liver belong functionally to the left love of the liver.

The functional organization of the liver refers to eight segments with I being the caudate lobe and moving left to right numbers II-VIII follow.

The functional arrangement aspects of the liver indicate that each segment has their own vascular and biliary pedicle and venous drainage and this facilitates segmental resections of the liver.

The normal adult liver weighs 1400-600 gm and represents 2.5% of the body’s weight.

Liver blood flow declines between ages of 20 and 90 by as much as 40%.

Liver size decreases between 20-25% in a lifetime.

Physical examination to assess liver size includes percussing the vertical span of the liver along the right midclavicular line during quiet respirations and listening for a dull sound, the lower edge of the liver is percussed along the right costal margin, where is the upper border is usually sharply defined by the air filled lung.

A palpable liver age below the right costal margin is often suggestive of underlying liver disease.

The liver normal size is approximately 8 cm, with 6 cm considered small and greater than 10 cm considered hepatomegaly.

By mid clavicular percussion the mean liver size for females is 7 cm and for males is 10.5 cm, with a liver size 2-3 cm larger or smaller than these values being considered abnormal.

Approximately 25% of total cardiac output arrives via the portal vein which is 60-70% of hepatic blood flow and the hepatic artery which has about 30-40% of flow through the hilum, the porta hepatic.

Portal vein carries venous blood to the liver from the gut, pancreas and spleen

The hepatic parenchyma serviced by approximately 450,000 terminal branches of the portal tract system.

Portal blood enters the parenchyma, the major bile ducts and the vasa vasorum of the major portal veins and the hepatic capsule.

Blood from all sources is collected into the hepatic vein and leaves the liver apposed to the inferior vena cava.

Divided into 1-2 mm hexagonal lobules oriented around terminal tributaries of the hepatic vein (terminal hepatic veins) with portal tracts at the periphery o the lobules.

Hepatocytes near the terminal hepatic vein are called centrilobular and those near the portal tract are named periportal.

Centrilobular hepatocytes are the most distant from the blood supply.

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